// Copyright 2023 The Tint Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef SRC_TINT_LANG_CORE_IR_TRAVERSE_H_
#define SRC_TINT_LANG_CORE_IR_TRAVERSE_H_

#include "src/tint/lang/core/ir/block.h"
#include "src/tint/lang/core/ir/control_instruction.h"
#include "src/tint/utils/containers/reverse.h"
#include "src/tint/utils/containers/vector.h"
#include "src/tint/utils/traits/traits.h"

namespace tint::core::ir {

/// Traverse calls @p callback with each instruction in @p block and all child blocks of @p block
/// that matches the callback parameter type.
/// @param block the block to traverse
/// @param callback a function with the signature `void(T*)`
template <typename CALLBACK>
void Traverse(Block* block, CALLBACK&& callback) {
    using T = std::remove_pointer_t<traits::ParameterType<CALLBACK, 0>>;

    Vector<ir::Instruction*, 8> queue;
    if (!block->IsEmpty()) {
        queue.Push(block->Front());
    }
    while (!queue.IsEmpty()) {
        for (auto* inst = queue.Pop(); inst != nullptr; inst = inst->next) {
            if (auto* as_t = inst->As<T>()) {
                callback(as_t);
            }
            if (auto* ctrl = inst->As<ControlInstruction>()) {
                if (auto* next = inst->next) {
                    queue.Push(next);  // Resume iteration of this block
                }

                Vector<ir::Instruction*, 8> children;
                ctrl->ForeachBlock([&](ir::Block* b) {
                    if (!b->IsEmpty()) {
                        children.Push(b->Front());
                    }
                });
                for (auto* child : Reverse(children)) {
                    queue.Push(child);
                }
                break;
            }
        }
    }
}

}  // namespace tint::core::ir

#endif  // SRC_TINT_LANG_CORE_IR_TRAVERSE_H_